Aircraft engine starting device



Aug. l5, 1950 w. G. ovENs 2,518,712 .AIRCRAFT ENGINE STARTING 'DEVICE Filed June 23, 1945 Smm-En f-rdn.

IN VEN TOR l {ll/xlunyfeLPl/nn l I W/LL/AM GOT/EMS. O 25 SOTme l," 5650 90 120 i I ATTORNR? Patented Aug. 15, 1950 AIECRAFT ENGINE STARTING DEVICE William G. Ovens, Midland Park, N. J., assignor to Wright Aeronautical Corporation, a. corporation of'Ncw York Application June23, 1943,.Serial No. 492,193-

This invention relates to a system andrapparatus for providing automatic starting of an internal combustion engineand is particularly directed to the starting of an aircraft engine.

The starting of an aircraft engine involves the coordinated operation of numerous engine` starting instrumentalities. The procedure is complicated and requires considerable precision .and manual effort and may even require the cooperation of two men. Itis an object of this invention to providean apparatus'under the control of a push buttonwhich, when closed, automatically effects operation of the kengine'starting instrumentalities in the proper sequence and `for the proper duration. In other Words, lt'is an object of this invention to provide an apparatus'requiring only a single manual operation in'order to start an aircraft engine.

It is a further object of this invention to provide an automatic starting apparatusV for an engine, which apparatus requires only a single manual operation and which is' automatically capable of electing different starting programs Aas determined by existing temperature conditions. For example, the extent and character of the priming operation is determined by the temperature of thesurrounding atmosphere.

Specifically, the invention comprises an electric motor which, after it is set in operation, closes a holding circuit for itself to insure operation of the motor through a complete cycle. During the cycle the motor is adapted to close and open a plurality of switches in a predetermined sequence and these switches are adapted to control the vvarious engine starting instrumentalities. Y Other objects of this invention will become apparent upon reading'the followingspecilication in-connection with the drawing in'which:

Fig. l 'is a diagrammatic layout of the starting apparatus embodying the invention,

Fig.` 2 is va. graphical illustration of a typical starting program; and Y 'Figure 3 is a vview illustrating a'modied `portion of Figure 1.

Referring to the` drawing, the engine .starting lapparatus comprises anl electric motor I 0 drivably connected, either directly or through appropriate gearing, to a cam shaft I2. This camshaft is provided with a plurality of cams I4, I6, I8, 2|),V

22, 24, vand 2-6,inclusive. The circuit for the motor iii 2 closed. When the starter switch is closed the motor ID isv energized and drives the cam shaft I2' and as soon as the vcamshaft has rotated a small predetermined amount, the cam I4 simultaneously closes switches 34 and 3B. Switch l34 closes' a' holding circuit for the motor I 0 which circuit is held'yclosedlby the cam I4 untilthe shaft I2 completes one'V revolution. In this Way the cam I4 insures rotation of the motor I0 and its cam shaft through a complete cycle. Simultaneously with the closure of switch 34, switch 36 closes a circuit to the signal .lamp 38, Vthereby indicating that the motor holding circuit. has been closed and whereupon the operator may release the starter switch 30. l The starter switch 3D andthe motor holding circuit switch 34, when closed,both short circuit the signal lamp 32 and, therefore, energization of the signal la1np'32 when the master switch 28 is closed, indicates to the operator that the motor IQ is in position for starting a cycle. Y

lSimultaneously with the closing of the holdingv circuit, the cams I 6 and I8 operate to close switches 40 and 42 respectively. Switch 4Q, when closed, completes ajcircuit to the motor 44 which is drivably connected to` an auxiliary fuel pump '46. This fuel pump'46 replaces the hand operated and so-called "wobble pump which is generally used to build up fuel pressure before the engine driven -fuel pump is operating. Cam I6 isdesigned to hold switch 40 closed until just prior tc the end of the cycle whereby the auxillary fuel pump 46 operates practically throughout the cyclewhich iorr a particular model engine maybe -for `120 seconds,` as graphically illustrated in Fig. 2. The switch 42,' when closed' byjthe cam I8, completes a circuit to the engine starter motor 48 and this circuit is held closed for a period of 90 Yseconds from the start of the cycle.

The starter motor 48 is part of a conventional s'o-c'alled inertia starter 'in which an electric motor or manually operable means are used to energize an inertia wheel, andy after the inertia wheel is up toV speed a clutch is engaged to drivably Yconnect the inertia `l.wheel `with the engine tc be cranked. Patent 1,679,602y to R. Chilton illustrates such an inertia starter although, ob-

Y viously, any conventional inertia starter ymay be includes a battery 21, a `mrasterswitch 28, and a used. ThisV starter is'also provided kwitha'solenoid SI1-which when energized* drivably clutches or 'meshes the inertia wheel (not shown) driven by the motor 48,' with the Aengine to be started. The circuit of the .meshing solenoid 50 is opened and closed by switch 52 which in turn is controlled by the cam 24. -jThis cam is designed toclose the circuit to the meshing solenoid 30 seconds after the beginning of the starting cycle and to open the circuit of the solenoid 90 seconds from the start of the cycle. That is, the meshing solenoid automatically effect-s engagement of the starter inertia wheel with the engine after the starter motor 48 has operated for 30.1seconds and presumaby has driven the inertia wheel to the desired speed.

In an aircraft engine the electric energy re-' quired by the ignition circuit is normally supplied by a magneto. Accordingly, auxiliary ignition apparatus is required during the starting operation and for this purpose it is common practice to provide a conventional vibrator-type ignition coil. Thus, in Fig. 1 a vibrator-type ignition coil 54 is connected to the switch 56 controlled by the cam 22. The switch 56 energizes the ignition coil during the same portion of the starting cycle as the meshing solenoid is energized by the switch 52, as graphically illustrated in Fig, 2. The secondary winding 53 of the ignition coil'is connected to the usual ignition distributor (not shown).

In addition to the above apparatus, in general it is necessary to prime the engine in order to start it. With a particular engine model it has been found that with an atmospheric temperature in excess of 100c7 F. no priming is necessary, with a temperature between and 100 F. t ie standard aircraft fuel is satisfactory for priming, but with a temperature below 20 F. a special priming fuel is required. To meet these requirements a primer pump 60 has its outlet connected to the conventional priming nozzles in the induction system of the engine through a conduit 62. The intake of this pump 60 is connected through a solenoid valve 68 and a conduit 'l0 to a supply tank containing a special priming fuel, or this pump is connected through the solenoid valve 66 to .the conduit 64 which is supplied with standard engine fuel by the pump 46. The-pump 46 has its intake side connected to the standard fuel supply tank of the aircraft through a conduit 12. This priming system is controlled by the cam 20 through a cam controlled switch 'I4 and a thermostatic element 16. Fuel priming control switch 'E4 is adapted to be closed 25 seconds after the start of the cycle, and remains closed until the end of the cycle, as graphically illustrated in Fig. 2. The switch 14 is connected to a contact portion 'I8 carried by the thermostatic element 'i6 and which contact portion is adapted to wipeover the cooperating contacts 80, 82, and 84 with change in temperature. Contacts 18 and 80, when engaged, complete a circuit from the cam switch 14 tothe electric motor 86 for driving the priming pump E0. Contacts 82 and 84 are connected to solenoids 88 and 90, respectively. Contact portion 18 of the thermostatic element 16 is arranged to engage the contact-82 between 20 and 100 F. and to engagethe contact 84 below 20 F., and at the same time to engage the contact .80 throughout these temperature ranges. Above 100 F. all circuits through the thermostat contact portion I8 are broken and a signal lamp circuit is completed by contact portion 92 of the thermostatic element, bridging the spaced contacts 94 and 96 to energize the signal lamp 98. With this construction when the cam 20 closes switch I4 if the temperature is below 20 F. solenoid valve 68 is opened and the priming pump 60 supplies priming fuel to the priming nozzles from the special priming fuel supply through the line 10. If the temperature is between 20 and 100 F. then when the cam switch '14 is closed the solenoid valve 66 is opened instead of the valve 68, whereupon the priming pump 60 operates to supply standard engine fuel to the priming nozzles. If the temperature rises above 100 F. the priming pump 60 will not be energized and thesignal lamp 88 will indicate this fact to the operator.

The signal lamp 68 may also be energized by closure of the cam switch |06 by cam 26. This cam is adapted to close switch |20 approximately 10 seconds. prior to the completion of the starting cycle and to hold this switch closed for the remainder of the cycle. In addition, signal lamp 98 may be energized by the closure of switch |02 by engine manifold pressure responsive means This pressure responsive means is connected to the engine intake manifold through a conduit connection |06." A flexible diaphragm |08 is disposed across the housing of this pressure responsive means to form a chamber I0 and is subjected to the engine manifold pressure on one side while the opposite side of this diaphragm is exposed to atmospheric pressure. The diaphragm |08 is connected to the dashpot H4 byla rod ||6 having a. piston head ||8 slidably received within the dashpotk housing which is provided with a restricted vent |20. The dashpot thereby operates to retard any upward movement of the rod I6 and the connected diaphragm |08..

Therefore, as soon as the engine is operating smoothly the resulting drop in engine manifold pressure results in continued upward movement of the diaphragm |08 against the bias of spring |I2. The rod ||6 is provided with a projecting collar |22 which is arranged to close the switch |02 as soon as the engine is operating smoothly and, in addition, a normally closed switch |24 is disposed relative to the collar |22 and switch` |02 so as to be opened approximately 10 seconds after the closure of the switch |02.

. In this way the switch |24 is arranged to open the battery connection to the switches controlled by the cams 6, I', 20, 22, 24, and 26 after the engine has maintained a predetermined intake manifold pressure for approximately 10 seconds, that is, after the engine is running smoothly. Thus, if the engine starts before the end of the starting cycle the various starting instrumentalities are (ie-energized within 10 seconds by the opening of the switch |24. However, the holding switch 34 insures continued operation or -the motor I0 to the end of its cycle in order that the motor I3 be at the proper initial position for the r next starting operation. Also at this point it should be noted that, although the means forv interrupting the starting program after the engine is operating has been disclosed as being responsive to the engine intake manifold pressure, other means indicative of engine operation may be used as, for example, means responsive to the speed of the engine as hereinafter described `in connection with Figure 3. Y

A normally closed safety switch |26 is provided to permit the operator to shut down the starting :apparatus in case some emergency should arise. This switch |26, like the switch |24, when open disconnects the battery from the various switches controlled by the cams |6, I8, 20, 22, 24, and 26. Although the various starting functions may be interrupted by the opening of switch |24 or |26, the motor circuit holding switch 34 insures continued operation of the motor I0 to the end of the cycle in order to insure return of this motor to its proper initial position.

' AFrom the above description it is apparentv that vthe signal lamp98 maybe energized by the clonot start `until near the Yvery endof the cycle lamp 98 is closed by switch |00, 10 seconds before the end of the cycle to apprisefthe operator ofthe approach of the'end of the starting cycle. The operator thereupon adjusts the carburetor to supply the normal fuel mixture to insure a continued supply of fuel after the fuel priming operationA ceases. During thev starting cycle the engine throttle is only opened suiiiciently: to insure an air supply sufficient for thecombustion of the priming fuel while the fuel mixture control is in its cut-off position. If the engine-starts to run considerably before the end of the cycle the lamp $.18` is energized by the closure of switch |62 and, since the switch |24 opens 10seconds later to interrupt the various starting functions, this energization of the lamp 98 also indicates to the operator that the starting operation will end in l0 seconds and, therefore, thatit is necessary to properly adjust the engine fuel mixturecontrol. If the atmospheric temperature happensto'be above 100 F. at the start of the cycle, the signal lamp; 98' will immediately be energized through ycontacts 94 and 96 upon closure of the master switch |28. This willinform the operator that fuel priming is not necessary and will not be provided by the starting apparatus. Thereupon the operator will properly adjust the carburetor fuel mixture control. In other words, theenergiza- Ationjof lamp 98 will always inform the operator 'of the need for adjusting the fuel mixture control. n

It is also desirable to control the operation of the fuel priming pump 60 in accordance with the atmospheric temperature conditions. Thus, when the temperature is quite cold only a small percentage of the fuel volatilizes so that a greater `supply of priming fuel is required. To meet this requirement the speedl ofthe pump y6|! is controlled by a temperature responsive resistance |28 properly connected into the circuit of the` electric motor 86. In this Vway the speed of the pump `6|) vis less at higher temperatures because of the increase in the magnitude of the resistance |28.

In thev above description the specific temperav ture limits and the specific duration and sequence of the variousy phases of the starting cycle are only typical of a particular engine'model. Obviously,` the invention is not limited to these specie, details sincethe starting procedure naturally varies with different engines. In addition, some of the starting functions may be manually controlled, or, if desired, additional starting functionsmay be included.

As previously mentioned, Figure 3 illustrates.:-

a modification in which engine'speed, instead of engine manifold pressure, is used for interrupting the engine starting program. In Figure 3, a shaft, diagrammatically indicated lat |39, is driv- Yably connected to the engine to be started and? is provided with ilyweights 32 pivotally mounted thereon. The ilyweights |32 are. connected to a sleeve H6' having at its lower'end a piston Ill-S' slidably received Within a `dash pct housingV IIA' which, in turn, is provided 'with a restricted venti:

|20'. With this construction, as the engine yapproaches a predetermined speed, the ilyweights |32 move outwardly thereby raising the sleeve H6 and its piston H8 against a spring H2. 'Ilhe sleeve ||6 has a collar |22 arranged to ,l be clear without further description.

Therefore, while I -have described my invenltionin detail in its present' preferredembodiment, it will be obvious t'othose skilled inthe art, Yafter understanding my invention, that various lchanges and modifications maybe made therein Without departing from `the spirit or scope therepf. vI aim in the appended claims to cover all such modifications and changes. I

`I claim as myinvention: 1.` Mechanism for controlling the activationof k-a -plurality'of instrumentalities .for starting an engine,fsaid mechanism comprising motor means, a-'plurality-of means each operable `-to effect a particular starting function by controlling the activation of one of said instrumentalitiesmeans responsive to operation 0f said motor means to eiect a, predetermined program of operationof :said plurality of'means, and'means responsive f to the engine manifold pressure for interrupting v'said program.

2. Mechanism for controlling the activationof y'a pluralityof instru'mentalities for starting an engine, said mechanism comprising motor means, a plurality of means each operable'to effect a lparticular starting function by controlling the activation of one of said instrumentalities, one

of said plurality of means being operable to effect priming of the engine as its starting function, means responsive to operation of said motor means to eiect a predetermined program elf oper'- ff ation of said plurality of means, means responsive -r`to the temperature of the surrounding air, and 40 rcontrolling said priming operation.

means controlled by saidv responsive means Vfor 3. Mechanism for controlling the'activation `of Ea plurality of instrumentalities for starting Yan engine, said mechanism comprising -a cyclically operable motor, a, plurality of means each oper- 5able to effect a particular starting function-by controlling the activation of one of said instrumentalities, means responsive to operationof said motor to elect a predetermined program of operation of said plurality of means, mea-ns responsive to engine starting to interrupt said program, means to insure completion of the motorA cycleeven vthough' the starting program is interrupted, fand means to indicate completion of the. motor cycle.

'4. Starting control mechanism for an engine nism comprising motor means, means automatimeans'to effect operation of the auxiliary fuel f pump vand the startermotorv of said inertia starter andto subsequently effectY energization ,65j of' said' auxiliary ignition circuit and to drivably i connect'` theinertia Ywheel of said` starter 'with -said engine.- and means responsive to r engine starting for terminating the operation of" said inertia starter, auxiliary fuel pump and auxiliary ignition circuit;

ing by each controlling the activation of one of said instrumentalities, means responsive to operation of said motor means to effect a predetermined program of operation of said plurality of means, means responsive to a condition of the surrounding air, and means controlled by said condition responsive means for automatically controlling the quality of the priming fuel.

.6. Mechanism for controlling the activation of a pluralityof instrumentalities fcrstai-ting an engine, said mechanism comprising acyclically operable motor, a plurality of means'each operable to eiect a particular starting function by controlling the activation of one of said instrumentalities, means responsive to operation of said motor to effect a predetermined program of operation of said plurality of means, means responsive to engine starting or to completion of a motor cycle for terminating said program, and indicating means operative a predetermined interval prior to said termination. A

7. Mechanism for controlling the activation of a plurality of instrumentalities for starting an engine, said mechanism comprising a motor, a plurality of means each operable to effect a particular starting function by controlling the activation of one of said instrumentalities, means responsive to energization of said motor to effect operation of said plurality of means in a predetermined sequence, and means operable to interrupt the operation of said plurality of means at any time, said motor automatically returning to its initial position for a subsequent starting operation upon said interruption of the operation of said plurality of means,

8. Mechanism for controlling the activation of a plurality of instrumentalities for starting an engine, said mechanism comprising motor means,

a. plurality of means each operable to effect a particular starting function by controlling the activation of one of said instrumentalities, means responsive to operation of said motor means to effect a predetermined program of operation of `said plurality of means, means responsive to the attainment. of an engine condition indicative of engine starting for interrupting said program, and indicating means operative a predetermined interval prior to said program interruption;

9. Mechanism for controlling the activation of .a plurality. of instrumentalities for starting an engine, said engine being operable thereafter independently of said instrumentalities which include a fuel pump, fuel priming means, and a.

starter unit for providing said engine withstarting torque; said'mechanism comprising means .to effect a predetermined program of operation of said instrumentalities such that operation of said fuel pump and fuel priming Imeans are inirtiatedbefore said starter unit is rendered effecltive to provide. said engine With starting torque and both said operations continue for a time after said starter unit is rendered ineffective.

10. Mechanism for controlling the activation of a plurality of instrumentalities for starting an engine, said engine being operable thereafter independently of said instrumentalities Which `include a, fuel pump, an ignition circuit, fuel priming means, and a starter unit for provid- Y ing said engine with starting torque;l said mechanism comprising means to effect a predetermined program of operation of said instrumentalities such that the operation of said fuel pump and said fuel priming means are initiated before said ignition circuit is energized and before said starter unit is rendered effective to provide said engine with starting torque and both said operations continue fora time after said ignition circuit is de-energized and said starter unit .is rendered ineffective.

11. Mechanism for .controlling the activation of a plurality of instrumentalities for starting an engine; l said mechanism comprising motor means; `a plurality of means each operable to effect a particular starting function, by controlling the activation of one of said instrumentalities, one of said plurality of means being operable to effect the supplying of fuel to Said engine as its starting function; means responsive to operation of said motor means to effect a predetermined program of operation of said plurality of means; means responsive to the surrounding air temperature; and means controlled by said temperature responsive means for regulating the fuel supplied to said engine during said program.

i2. Mechanism for controlling the activation of c, plurality of instrumentalities for starting an engine; said mechanism comprising motor means; a plurality of means each operable to effect a particular starting function by controlling the activation of one of said instrumentalities; means responsive to energization of said motor means to effect operation of said plurality means in a predetermined sequence; and means operable to interrupt the operation of said plurality of means at any time, said motor means automatically returning to its initial condition for a subsequent starting operation upon said interruption of the operation of said plurality of means.

13. Mechanism for controlling the activation of a plurality of instrumentalities for starting an engine; said mechanism comprising motor means; a plurality of means each operable to effect a particular starting function by controlling the activation of one of said instrumentalities, one of said plurality of means being operable to effect priming of the engine as its starting function; means responsive to operation of said motor means to effect a predetermined program of operation of said plurality of means; means responsive to a condition of the surrounding air; and means controlled by said condition responsive means for controlling said priming operation.

WILLIAM G. OVENS.

REFERENCES CITED The following references are of recordin the file of this patent:

'UNITED STATES PATENTS Number Name Date 1,470,948 Van Horn Oct. 16, 1923 1,705,816 Ide Mar. 19, 1929 1,706,119 Jones Mar. 19, 1929 1,965,372 Drabelle July 3, 1934 2,015,309 Igarashi Sept. 24, 1935 2,147,019 Ericson Fe'b. 14, 1939 2,301,071 Nardone Nov. 3, 1942 

